Are email addresses case sensitive?

Email addresses are composed of two parts: the username and the domain. The username is to the left of the @ symbol and the domain name (which the username is created on) is to the right side. For example:


Both domains and usernames can include letters, numbers, and symbols, but what about capital and lowercase letters?

Are email addresses case sensitive?

Domain names are case insensitive so,, and all go to the same place. Therefore, the domain side of the email address is case insensitive.ย 

However, the username side of email addresses can contain uppercase and lowercase letters. The difference with usernames is that most email clients interpret uppercase and lowercase letters differently so most of the time [email protected] is different than [email protected]

This does depend on the email client and how they process email address usernames. For example, Gmail processes email addresses with periods and mixed in the middle the same way. Therefore [email protected] is the same as [email protected] Both are the same as [email protected]


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